An example of corrugated fins is shown in FIG. 11. The shown corrugated fin 10 is a flat corrugated fin, in which ribs 12 are vertically formed with respect to a metal plate 9.
In the corrugated fin 10, the metal plate 9 is composed of, for example, aluminum, and the ribs 12 are continuously formed. The corrugated fin 10 is used in a radiator of a vehicle, a heat exchanger of an air conditioner, EGR (Exhaust Gas Recirculation), etc.
Several conventional production equipments for producing the corrugated fin 10 have been known. Japanese Laid-open Patent Publication No. 4-371322 discloses a production equipment for producing a corrugated fin, in which a punch and a die are closed, by one press action of a press unit, to form one rib.
Japanese Laid-open Patent Publication No. 2006-263815 discloses a production equipment for producing a corrugated fin, in which a plurality of punches are sequentially moved toward a plurality of dies. The ribs can be efficiently formed by one die-punch closing action.
Further, Japanese Laid-open Patent Publication No. 9-155461 discloses a lifter for lifting a non-ribbed part, in which a rib is still not formed, upward after forming a rib in another part. In the production equipment disclosed in Japanese Laid-open Patent Publication No. 9-155461, when a lower block and an upper block are opened after completing the closing action of the both for forming the rib, the lifter is moved upward to separate a ribbed part of a metal plate from a die provided to the lower block, and then the metal plate is horizontally moved to form the next rib.
These days, a height of ribs (a depth of grooves between ribs) of a corrugated fin has been increased so as to enhance heat exchange efficiency.
However, if the height or depth is excessively increased, a punch or die will bite a metal plate. Even if the lifter is provided, the metal plate cannot be easily separated from the punch or die.